The United States upset Ireland 2-1 to draw their two-match series in Dublin.
The visitors, who are ranked 26th in the world and 16 spots below Ireland, scored twice in the final quarter to surprise their hosts.
Ireland, who won Thursday's opening game 5-1, led at half-time thanks to Shane O'Donoghue's low strike.
But Kei Kaeppler levelled for the US before William Holt secured a stunning victory with a late winner after Ireland had switched to a kicking back.
Following on from their comfortable win in the opening match of the series, Ireland looked in control for most of the game at Pembroke hockey club, with John McKee and O'Donoghue both going close in the opening minutes.
The home side deservedly took the lead from their third penalty corner when O'Donoghue rifled a shot into the bottom corner of the goal.
The US improved in the second half and drew level with a superb goal by Kaeppler, who picked up the ball at the top of the circle and volleyed into the top corner.
Ireland pulled goalkeeper Mark Ingram in favour if a kicking back as they went in search of a winner but the gamble did not pay off as Holt scored in the dying minutes when he pounced on a deflection and scored into an open goal.